Readers' comments

Any readers understand (1) how Ithaca, NY could generate infrasound unlike other places' infrasound, (2) in specifically what way Jersey Hill suppressed infrasound from the Ithaca generator or (3) why pigeons released in Jersey Hill could not make do with just Earth's magnetic lines and the Sun to determine in what direction Ithaca lay?

The definitive answer to avian navigation is not known. Pigeons usually perform a few circles to determine their home loft direction and then they track and fly hard at up to 60 mph until they arrive home (and they can't afford to get lost for their avian metabolism is high and their "fuel tank" small). They have to compensate for crosswinds. Pigeons have been subjected to wearing frosted contact lenses, magnets, electromagnets, and been placed in Helmholtz coils and/or geomagnetic shields during transport to their release sites and still they home just fine. Considering physics can only explain 4% of matter (known periodic table) and that 96% of matter is unknown (dark matter) not to mention dark energy and remember we are being bombarded by trillions of neutrinos per second (that have directional information), we need to be a bit skeptical. Personally, I am in awe of these pigeons for I truly believe they are using a force unknown to science that when discovered will be ridiculously simple because it was staring at us all the time. If only the pigeons could talk and tell us...

Think about the wavelength of these infrasonic waves and then think about the birds head width. To constantly determine the direction of these infrasonic waves would require using the Doppler shift as flying into the waves would increase the frequency and flying away would decrease the frequency. Without using Doppler, then the bird's head would have be wider than 17 meters (velocity of sound=frequency x wavelength where velocity=344 m/s and the frequency being 20 Hz or w=v/f) of the sound to discriminate the phase or time difference of arrival like owls use (but their hearing is ultrasonic and frequency is 100 KHz so wavelength is (344m/s)/100,000=0.344 cm). Compare 0.344cm to 17 m (and I was being conservative at using 20 Hz which is the lower threshold of human hearing).

So why pigeons who never saw the sun can't find their way home ? Or why do they stop their trip at night ? And pigeons are disoriented by magnetic perturbations.. Like solar storm, some military stuff, etc.
This study looks wierd. Or maybe TE is hiding us the important content.

I read in Science magazine years ago that many birds that migrate long distances can detect the polarization state of light, and that sunlight is somewhat polarized at sunrise and sunset. Furthermore, when some birds travel to high latitudes, the north magnetic pole drifts away from true north. For example, it is almost due east in northern Alaska. The particular paper in Scinece claimed that they had been able to determine that some birds stop after a few days of flying, use the sun to determine the approximately correct orientation of true north, and recalibrate their internal magnetic compass so that they are not tricked by the high latitude missmatch between geographic and geomagnetic north. As for infrasound, it is hard to figure out how such a small bird head can determine the direction from which infrasound is emanating. Maybe they can hear it get louder as they approach and decrease in volume as they fly away, and so get some sense of direction from it.

I recall that biologist Rupert Sheldrake explained the pigeons' navigation ability by collective consciousness. Now it seems that we need to reserve that explanation to the company managers with share options: the share prices tend to correlate; assuming pay is fair, managers must possess collective consciousness - but not to forget that the Atlantic waves also tremble the shores nearby the Wall Street.

Not sure if this applies to pigeons, but other species (e.g., bees) manage the same trick by having a built-in version of an Ephemeris Table (used by human navigators to solve the same problem...you need to know where the sun will be at a particular time on any given day of the year to use it as a navigational aid). This requires knowing both the time of day and the time of year and what that says about where the sun should be, but if a bee can manage it I suspect a bird, with much more brain, could as well.